Ageing and dementia: age-period-cohort effects of policy intervention in England, 2006–2016

BACKGROUND: Dementia is one of the most critical challenges of our time. According to the Dementia Statistics Hub, only about 66 % of all UK residents with dementia were diagnosed in 2017–2018. Yet, there are reservations about the early diagnosis of dementia-related diseases. As a result, the UK National Screening Committee does not recommend systematic population screening of dementia, although case-finding strategies are still applied for high-risk groups. METHODS: This study added additional evidence of the effectiveness of the National Dementia Strategy and increased numbers of diagnosis of dementia on the younger cohorts of the older people, using the intrinsic estimator age-period-cohort (APC) models and the English Longitudinal Study of Ageing data. RESULTS: Age effects show that diagnosis increases in volume only among those aged 75 and above, suggesting that many of those aged below 75 might not be diagnosed in time. Period effects show that although there was an initial increase due to the new policy implementation, the trend stalled in later years, indicating that the increase might not have been even across the period when controlled for age and cohort. The study also shows that cohort effects indicate lower prevalence in younger cohorts controlled for age and period effects. CONCLUSIONS: Although more research in diverse contexts is warranted, this study cautions against the abandonment of timely diagnosis, increased screening and case-finding, and shows some effectiveness of prevention strategies on the national level.